1. Field of the Invention
The present invention relates to a suspension for disc drive used in an information processing apparatus, such as a personal computer.
2. Description of the Related Art
A hard disc drive (HDD) is used in an information processing apparatus, such as a personal computer. The HDD includes a magnetic disc that rotates around a spindle, a carriage turnable around a pivot, etc. A suspension for disc drive is disposed on an arm of the carriage.
The suspension for disc drive includes a load beam fixed to the carriage, a flexure located overlapping the load beam, etc. A slider is mounted on a tongue portion that is formed on the flexure. The slider is provided with a transducer for reading or writing data.
Flexures of various forms have been put to practical use according to required specifications. As an example of these flexures, there is a flexure with conductors described in Jpn. Pat. Appln. KOKAI Publication No. 9-128727 or 9-128728. The flexure with conductors include a metal base member formed of a thin stainless steel plate, a resin base member formed of an electrically insulating material, such as polyimide, a plurality of copper conductors, etc. The resin base member is formed on the metal base member. The conductors are formed on the resin base member.
FIG. 12 shows a part of a conventional flexure 1 with conductors. The flexure 1 includes a metal base member 2 and a circuit member 3 formed thereon. The circuit member 3 includes a resin base member 4 formed of polyimide for example, conductors 5a and 5b formed of copper, a resin cover member 6, etc. In manufacturing the flexure 1 with conductors, resist films (not shown) corresponding to circuit patterns are formed on the resin base member 4. Further, the conductors 5a and 5b are formed by electrodepositing copper on that part of the surface of the resin base member 4 which is not covered by the resist film.
The conductors 5a and 5b are individually deposited between the resist films on the resin base member 4. Thus, the cross section of each of the conductors 5a and 5b is rectangular. Thus, the upper and lower surfaces of each of the conductors 5a and 5b share a width W3 in common. As shown in FIG. 13, moreover, portions that are provided with the circuit member 3 only are formed by removing a part of the metal base member 2 by etching. Also in this case, each of the conductors 5a and 5b has a rectangular cross section.
A bending stress may act in the thickness direction in some flexures with a circuit member. In these flexures, the peel strength of the conductors on the resin base member is expected to be enhanced. However, the peel strength of the conventional conductors against bending can be enhanced only limitedly.
Possibly, the conductors may be disposed on the resin base member by laminating thin rolled copper sheets on the resin base member. However, rolled copper contains a certain percentage of additional elements (e.g., several percent or less of nickel, silicon, etc.). Since rolled copper is lower in electrical conductivity than deposited copper (pure copper), therefore, it may fail to deal with high-speed transfer of read or write signals. In addition, the bending stiffness of rolled copper is higher than that of deposited copper. Thus, if the circuit member with the conductors formed of rolled copper bends in its thickness direction, its spring characteristics may possibly adversely affect the roll or pitch static attitude of the slider.